Genetic History of Cocoa in Brazil Uncovered

In 2015, cocoa growers in Brazil resumed exporting cocoa, after more than 20 years of crop losses and being exiled from the global market. The decline of Bahian cocoa was due to witch's broom caused by the fungus Moniliophthora perniciosa.

Anete Pereira de Souza, professor at the University of Campinas's Biology Institute (IB-UNICAMP) in São Paulo State, in collaboration with researchers from several universities and research institutions in Bahia studied the genetic structure and molecular diversity of cocoa varieties grown in Bahia for over 200 years. Souza and colleagues sequenced the nuclear DNA of 270 samples, and focused on 30 molecular markers. They found that the genetic base of Bahian cocoa is very narrow, and all of Bahia's cocoa trees are the descendants of only a few individuals.

The researchers discovered trees growing on local farms that were resistant to witch's broom, and that displayed greater genetic diversity than the previously known hybrids. "The cocoa trees concerned were planted before the appearance of witch's broom and have never been attacked. That's why they were left intact and continued producing," Souza said. New hybrids from the disease resistant trees are now being obtained by plant breeders at Bahia's research centers.

For more about this story, read the news release from Agência FAPESP.